Daniel Gralath (30 May 1708 – 23 July 1767) was a physicist and a mayor of Danzig.
Gralath was born in Danzig (Gdansk) in Poland of a well-to-do trade family. He had studied law and philosophy in Halle, then in Leyden and Marburg from 1728 to 1734. Later he became councilman and, in 1763, mayor of Danzig. His father-in-law was Jacob Theodor Klein (1685–1759), a city secretary and also a very distinguished scientist, nicknamed Gedanensium Plinius. He died in Danzig.
As a physicist, Gralath worked on electricity, founded the Danzig Research Society, and repeated the experiments of Ewald Georg von Kleist with the Leyden jar. Gralath improved the design and demonstrated its effects on a chain of 20 persons. He was also the first to combine several jars to make a battery. From 1747 to 1756, he published his "History of Electricity" with three volumes.